Influence of metal ions on bioremediation activity of protocatechuate 3,4-dioxygenase from Stenotrophomonas maltophilia KB2

The aim of this paper was to describe the effect of various metal ions on the activity of protocatechuate 3,4-dioxygenase from Stenotrophomonas maltophilia KB2. We also compared activity of different dioxygenases isolated from this strain, in the presence of metal ions, after induction by various aromatic compounds. S. maltophilia KB2 degraded 13 mM 3,4-dihydroxybenzoate, 10 mM benzoic acid and 12 mM phenol within 24 h of incubation. In the presence of dihydroxybenzoate and benzoate, the activity of protocatechuate 3,4-dioxygenase and catechol 1,2-dioxygenase was observed. Although Fe³⁺, Cu²⁺, Zn²⁺, Co²⁺, Al³⁺, Cd²⁺, Ni²⁺ and Mn²⁺ ions caused 20–80 % inhibition of protocatechuate 3,4-dioxygenase activity, the above-mentioned metal ions (with the exception of Ni²⁺) inhibited catechol 1,2-dioxygenase to a lesser extent or even activate the enzyme. Retaining activity of at least one of three dioxygenases from strain KB2 in the presence of metal ions makes it an ideal bacterium for bioremediation of contaminated areas.     

Antiovulatory antagonists of LHRH related to antide

We report 104 analogues of the potent antiovulatory antagonist of LHRH, N-Ac-D -Nal-D -Cpa-D -Pal-Ser-Lys(Nic)-D -Lys(Nic)-Leu-Ilys-Pro-D -Ala-NH₂, Antide. We replaced the Nic group in Antide with other acyl substituents to modulate size, hydrophilicity or basicity of the molecule, we also replaced th Lys residues with shorter basic amino acids, and made cyclic 5/6 analogues as well as position 5 or 6 dimers. We substituted Ilys⁸ with other alkyl groups and acyl derivatives. When injected in 0.1% DMSO in water in a typical antiovulatory (AO) assay, Antide gives six rats ovulating out of eight (6/8) at 2 μg, 4/8 at 4 μg, and the histamine release assay (HRA), ED₅₀ is >300 μg/ml; [Lys(N-Isobutyl)⁸]Antide gave 2/8 at 2 μg/rat; [Lys (8-Qis)⁵]Antide gave 1/8 at 1 μg, and 0/8 at 2 μg, and in the HRA ED₅₀, 22 μg/ml; [D -Lys(8-Qis)⁶]Antide gave 4/8 at 1 μg and 0/8 at 2 μg, and in the HRA, ED₅₀ was 27 μg/ml; [Lys(8-Qic)⁸] gave 5/8 at 1 μg, 1/8 at 2 μg/ [Lys(2-Pyc)⁵]Antide gave 5/8 at 1 μg and 0/8 at 2 μg, and in the HRA ED₅₀ was 116 μg/ml; [D -Lys (2-Pyc)⁶]Antide gave 3/8 at 1 μg, and in the HRA, ED₅₀ was 100 - >300 μg/ml; [Lys(2-Pyc)⁵,D -Lys(2-Pyc)⁶]Antide gave 2/8 at 1 μg. The substitutions of the Nic groups of Antide at Lys⁵ or D -Lys⁶ with 8-Qis or with 2-Pyc groups seem to give highly potent antiovulatory antagonists of LHRH and constitute significant new leads to generate potent antiovulatory compounds endowed with moderate or low histamine release.     

Dechlorination of three tetrachlorobenzene isomers by contaminated harbor sludge-derived enrichment cultures follows thermodynamically favorable reactions

Dechlorination patterns of three tetrachlorobenzene isomers, 1,2,3,4-, 1,2,3,5-, and 1,2,4,5-TeCB, were studied in anoxic microcosms derived from contaminated harbor sludge. The removal of doubly, singly, and un-flanked chlorine atoms was noted in 1,2,3,4- and 1,2,3,5-TeCB fed microcosms, whereas only singly flanked chlorine was removed in 1,2,4,5-TeCB microcosms. The thermodynamically more favorable reactions were selectively followed by the enriched cultures with di- and/or mono-chlorobenzene as the main end products of the reductive dechlorination of all three isomers. Based on quantitative PCR analysis targeting 16S rRNA genes of known organohalide-respiring bacteria, the growth of Dehalococcoides was found to be associated with the reductive dechlorination of all three isomers, while growth of Dehalobacter, another known TeCB dechlorinator, was only observed in one 1,2,3,5-TeCB enriched microcosm among biological triplicates. Numbers of Desulfitobacterium and Geobacter as facultative dechlorinators were rather stable suggesting that they were not (directly) involved in the observed TeCB dechlorination. Bacterial community profiling suggested bacteria belonging to the phylum Bacteroidetes and the order Clostridiales as well as sulfate-reducing members of the class Deltaproteobacteria as putative stimulating guilds that provide electron donor and/or organic cofactors to fastidious dechlorinators. Our results provide a better understanding of thermodynamically preferred TeCB dechlorinating pathways in harbor environments and microbial guilds enriched and active in anoxic TeCB dechlorinating microcosms.

     

Control of Hydrogen Photoproduction by the Proton Gradient Generated by Cyclic Electron Flow in Chlamydomonas reinhardtii

Hydrogen photoproduction by eukaryotic microalgae results from a connection between the photosynthetic electron transport chain and a plastidial hydrogenase. Algal H₂ production is a transitory phenomenon under most natural conditions, often viewed as a safety valve protecting the photosynthetic electron transport chain from overreduction. From the colony screening of an insertion mutant library of the unicellular green alga Chlamydomonas reinhardtii based on the analysis of dark-light chlorophyll fluorescence transients, we isolated a mutant impaired in cyclic electron flow around photosystem I (CEF) due to a defect in the Proton Gradient Regulation Like1 (PGRL1) protein. Under aerobiosis, nonphotochemical quenching of fluorescence (NPQ) is strongly decreased in pgrl1. Under anaerobiosis, H₂ photoproduction is strongly enhanced in the pgrl1 mutant, both during short-term and long-term measurements (in conditions of sulfur deprivation). Based on the light dependence of NPQ and hydrogen production, as well as on the enhanced hydrogen production observed in the wild-type strain in the presence of the uncoupling agent carbonyl cyanide p-trifluoromethoxyphenylhydrazone, we conclude that the proton gradient generated by CEF provokes a strong inhibition of electron supply to the hydrogenase in the wild-type strain, which is released in the pgrl1 mutant. Regulation of the trans-thylakoidal proton gradient by monitoring pgrl1 expression opens new perspectives toward reprogramming the cellular metabolism of microalgae for enhanced H₂ production.     

Serum alkaline phosphatase polymorphism in pigs1

Genetic variants of serum alkaline phosphatase were studied by the method of starch gel electrophoresis in the Zlotnicka Pstra breed of pigs. Two regions of alkaline phosphatase migration were observed. A single fraction in region I and four different phenotypes: AB, B, BC and BD in region II, were found. For AB, B and BC phenotypes the genetic control by three alleles AkpA, AkpB and AkpC in suggested. The observed segregation ratios in some cases deviated significantly from the expected ones.     

Field Studies on Circadian Rhythms of Core Temperature in Tropical Inhabitants Compared with Those in European Inhabitants

In order to know the characteristics of circadian rhythms in core temperature in tropical inhabitants, we measured rectal temperatures every 10 min for 50 h in 6 Vietnamese, 20-22 years old (5 males and 1 female) under natural conditions. Ambient temperatures ranged from 33 to 36°C. These data obtained in tropical inhabitants were compared with those in Polish inhabitants. The participants in both groups were usually sitting during wakefulness and lying in bed during sleep. The results obtained are summarized as follows: (1) The average maximum value was 37.7°C, which was significantly higher than in the Europeans; (2) The average minimum value was 36.2°C, which was lower; (3) A range of oscillation was 1.5°C, which was clearly greater than in the Europeans. The higher maximum value of core temperature, which was actively regulated under warm temperature, seemed of adaptive significance in order to reduce water consumption. A greater rage of oscillation in tropical Vietnamese people might have ecological significance for efficient acclimatization in the warm environment, suggesting that the setpoint of core temperature could show a greater range of oscillation.     

CD68 expression in aortocoronary saphenous vein bypass grafts

Atherosclerosis commonly affects the arteries harvested from patients 70 years of age or older. Saphenous vein grafts appear to maintain a higher patency rate after coronary artery bypass grafting in these subjects. The infiltration of macrophages is an early step in saphenous vein graft atherosclerosis; however, little is known regarding the underlying mechanisms of infiltration. The objective of the present report is to evaluate the presence of CD68-positive cells in the saphenous vein wall and correlate initial CD68-positive infiltration to specific clinical and biochemical parameters and the graft patency rate as estimated in patients undergoing coronary artery bypass grafting. A total of 309 patients were allocated into two groups: A1 patients, who were between 50 and 70 years of age, and A2 patients, who were 70 years or older at the time of vein harvesting. CD68 expression was evaluated by immunohistochemistry. There were no significant differences between A1 and A2 patients regarding macrophage expression within any of the analyzed vascular regions. Saphenous vein macrophages were never present in the tunica intima unless they were also expressed in the media or the adventitia. The patients with CD68-positive cells in the tunica intima had a significantly higher number of bypass stenoses when compared with the subjects who did not have CD68-positive cells in this layer. These findings suggest that the CD68-positive cells (those that have not yet developed into foam cells) present in the intima of saphenous vein grafts might serve as a very early marker of graft occlusion.